In line with development of information technology (IT), various portable information and communication devices have entered widespread use and thus the 21st century is developing into a “ubiquitous society” where high quality information services are available regardless of time and place. Lithium secondary batteries play a key role in such development towards the ubiquitous society. Lithium secondary batteries have higher operating voltage and energy density, are used for a longer period of time than other secondary batteries and thus can satisfy sophisticated requirements according to diversification and increasing complexity of devices. Recently, attempts to improve existing lithium secondary battery technology are actively underway around the world such that the existing lithium secondary batteries can be applied to eco-friendly hydrogen systems such as electric vehicles and the like, power storage systems, and the like.
Korean Application Pub. No. 10-2005-0114516 discloses a cathode active material for lithium secondary batteries including a lithium-containing composite oxide, a surface of which is coated with heterogeneous metal oxides.
Korean Patent No. 10-0479900 discloses a lithium-containing transition metal oxide having a spinel structure, in which some manganese (Mn) is substituted with at least one metal element selected from the group consisting of Ni, Co, Fe, Cr and Cu, and at least one metal element selected from the group consisting of silicon (Si) and titanium (Ti).